Custom HOME_SEARCH_VEL

Hello Guys 
For long time i trying to find any way to control the HOME_SEARCH_VEL for the calibration cycle, i'd like to link the signal to a knob that control the rapid speed as well 
Im not expert, im not sure if i got to create a  HAL thread to link the HOME_SEARCT_VEL
your help is appreciated
Regards
 

May I ask, what use case requires adjustable home_search_vel? Sorry for my ignorance.

is a long machine and is installed in a reduced space, the original numeric control had that function in order controlling the motion all the time for operators safety

Hello guys
Could you help me please?
Just i trying to use home_search_vel as a pin to link it i don't know how can catch it as a pin 
Your help is appreciated